TRIPOLI/LONDON, Jan 18 (Reuters) - Libya rushed to beef up
security at its oil fields and energy firms were considering
similar measures in Egypt as Islamist militants threatened to
attack new installations in north Africa.

More than 20 foreigners were still being held hostage or
missing inside Algeria's In Amenas gas plant on Friday after
Algerian forces stormed the desert complex near the Libyan
border to free hundreds of captives taken by Islamist militants.

Hundreds of workers were evacuated from a number of Algerian
production sites on the border with Libya to safer places in the
country's centre and industry experts said that could ultimately
lead to lower oil and gas production from the OPEC member state.

Libya and Algeria are Africa's third and fourth largest oil
producers with Libya also the largest oil reserves holder on the
continent. Together with Egypt they are important gas suppliers
to Europe and the budgets of all three countries are heavily
dependant on energy revenues.

Libya's oil protection force, affiliated with the defence
ministry, said there had been no reports of incursions into its
oilfields, where more guards and military personal had been
deployed and security patrols intensified inside and around the
sites around the clock.

"Due to events in the region, the Petroleum Faculty Guard
has taken a series of actions to enhance and reinforce the
protection of oilfields, facilities and employees in the western
and southern regions of Libya," it said.

A Western security adviser working in Libya said by
telephone he was not sure that would immediately boost security,
since the oil protection force, set up after the overthrow of
Muammar Gaddafi in 2011, was at an "embryonic stage".

Some Libyan oil fields such as Italy's Eni's
Elephant are located several hundreds of kilometers (miles)
across the desert from In Amenas, where the hostage tragedy
unfolded this week.

The militants said they attacked the facility in retaliation
for France's intervention in neighbouring Mali and warned
Algerians to stay away from sites with a foreign presence.

EXODUS

That attack and the warning triggered a mass exodus of
expatriates from Algerian oil and gas production sites and
security experts have said similar evacuation could be on the
way across other north African countries.

BP said on Friday hundreds of workers from
international oil companies had been evacuated from Algeria on
Thursday and many more would follow.

Crispin Hawes, from Eurasia consultancy, who said he had
visited the In Amenas site several times, said oil companies
removed non-essential staff in such circumstances as part of
their established protocols. "In other nearby countries, similar
responses are also almost automatically triggered," he said.

"Every international oil company operation in Algeria will
be obliged by insurers to take certain precautions to avoid and
mitigate such instances. Premiums are likely to rise and the
expatriation of staff will add to operating costs".

He said the exodus of expats might delay some projects but
added that very big outages were unlikely as the biggest fields
in southern Algeria such as Hassi Mesaoud were "extremely
secure".

NOT SO SECURE

Spain's Cepsa, which is the biggest foreign player in
Algeria operating the country's No.2 oilfield Ourhoud some 300
km (186 miles) north of In Amenas, decided to evacuate staff
towards the country's centre and away from the Libyan border, an
industry source said.

A source at Algeria's state oil firm Sonatrach, who works at
the country's top oil field Hassi Messaoud, said security had
been raised even though the deposit was 900 km (560 miles) away
from In Amenas.

"Automatically, when you have an incident like this,
security will be on alert, we prepare ourselves," he said.

A Western risk consultant, specialising on North Africa,
said the security situation in Algeria could not be beefed up as
quickly as in Libya.

"Westerners have been lulled by the idea that the state will
provide security. Now they may want to increase it, but Algeria,
being socialist, simply doesn't like the idea of private
security," he said.

People who have worked at the In Amenas plant say it was
heavily fortified, with security, controlled access and an army
camp with hundreds of armed personnel between the accommodation
and processing plant.

Even in Egypt, thousands of kilometers away from In Amenas,
the oil industry was feeling unnerved.

"If there is a critical situation (in Egypt) we will take
measures including staff evacuation. At the moment, everything
is under control," a spokesman for Russian oil major LUKOIL
said.

Royal Dutch/Shell, which has a heavy presence in
Egypt, said it was looking carefully at the geopolitical
situation to make appropriate security arrangements, but
declined specific country-related comments.

Chief executive of global oilfield services major
Schlumberger, Paal Kibsgaard, told a conference call on
Friday security in the entire region was under renewed scrutiny.

"If you talk about Algeria and Libya, we are operating there
with security measures and, with what has happened in the last
week, we are relooking at that," he said.